1. Field of the Invention
The present invention relates to a sealed structure including two substrates and a method for manufacturing the sealed structure. The present application claims priority under 35 USC §119 of Japanese application serial number 2011-227026 filed Oct. 14, 2011 in Japan.
2. Description of the Related Art
A technique in which a highly airtight sealed structure is formed in such a manner that two substrates are bonded to each other by a glass layer including low-melting glass is known. In a technique disclosed in Patent Document 1, a paste containing a binder and glass frit (denoted by a “frit material” in the document) including low-melting glass is applied to a glass substrate along an edge of the glass substrate, the binder is removed and the glass frit is melted to form a glass layer (denoted by a “frit glass” in the document) by baking of the paste, the glass layer is irradiated with a laser beam with the substrate overlapping with a counter substrate, and the glass layer is melted so that the substrate and the counter substrate are bonded to each other by the glass frit; thus, a highly airtight sealed structure is formed.
Since such a glass layer has a high gas barrier property, a space sealed with the glass frit can be kept away from the external atmosphere. A method for sealing with such a glass layer is used for a device including an element, such as an organic EL (electroluminescence) element, whose performance is rapidly decreased once the element is exposed to air (including moisture or oxygen).
As examples of the device including the organic EL element, a lighting device with the use of the organic EL element as a light source, an image display device in which a thin film transistor and an organic EL element are combined, and the like can be given. Since the organic EL element can be formed into a film and a large-area organic EL element can be easily formed, a lighting device including a planar light source can be provided using the organic EL element. In addition, an image display device using an organic EL element needs no backlight which is necessary for liquid crystal display devices and the like; therefore, thin, lightweight, high contrast, and low power consumption display devices can be obtained.